Microwave field effect transistors (FETs) are used extensively in various types of radio frequency (RF) circuits, such as power amplifiers, RF switches, and other circuits. In some RF circuits and devices, a “multi-gate” FET may be a more desirable option than a more conventional single-gate FET. Essentially, a multi-gate FET is a monolithic transistor device that includes a variable-conductivity channel between drain and source terminals, along with multiple gates positioned over the channel. Electrical signals provided to the multiple gates control the conductivity of the channel during operation of the FET. Implementation of multiple gates may enable better electrical control over the channel, when compared with single-gate FETs. This, in turn, may enable more effective suppression of “off-state” leakage current, and/or enhanced current in the “on” state (i.e., drive current).
A switch composed of a stack of multi-gate FETs (i.e., a series-coupled arrangement of several multi-gate FETs) may be implemented, in some systems, to achieve higher power handling capability. In such a switch, non-uniform, RF, alternating current (AC) voltage distribution across the stacked multi-gate FETs in an off-state may result in premature breakdown of the first multi-gate FET(s) in the stack, which in turn may degrade the power handling capability of the switch.